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Re: [RTL, i386] Use subreg instead of UNSPEC_CAST


On Wed, Mar 20, 2013 at 4:29 PM, Marc Glisse <marc.glisse@inria.fr> wrote:
> On Wed, 20 Mar 2013, Richard Henderson wrote:
>
>> On 03/20/2013 08:00 AM, Marc Glisse wrote:
>>>
>>> Do you at least agree that vector-vector subregs make sense, or is that
>>> part
>>> wrong as well?
>>
>>
>> You mean a V4SImode subreg of a V8SImode register, not just same-size
>> casting?
>
>
> I am mostly interested in the reverse, a paradoxical subreg, since
> vec_select can only model one direction (and only rvalues, but that's a
> different question).

vec_duplicate?

Honestly, what semantics should  _mm256_castpd128_pd256 have if
it is supposed to cast a v2df to a v4df?  Or what use?

Richard.


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